Manufacture of butadiene



Patented Aug. 21, 1945 1 William J. Mattox,

Riverside, 111., asslgn'or to Universal Oil Products Company,

Chicago, 111.,

a. corporation of Delaware No Drawing.

. .6 Claims.

This application ,is a continuation-in-part of copending application Serial No. 324,083 filed March 15, 1940.

The present invention relates to the manufacture of butadiene and is particularly concerned with a process whereby this compound can be made from the normal butane obtained incidental to the production of petroleum and from mixtures of normalbutane and normal butenes obtained incidental to the thermal and catalytic cracking of petroleum 'hydrocarbo The present invention is related to the problem of producing synthetic rubber from cheap and readily available organic materials. It has already been shown that butadiene may be poly merized by metallic sodium or other catalysts to form an excellent synthetic rubber and the present inventionis concerned with the production of the basic raw material by a special process.

One specific embodiment of the present invention comprises a process for the manufacture of butadiene by converting a butanediol to a butanediol diacetate and then decomposing the resulting diacetate into butadiene and acetic acid at from about'400 to about 600 C. by subjecting it to contact with an oxide of an element in the left-hand column of group ,IV ofthe periodic table.

It is well known in the art that normal butane may be converted to normal butenes either by direct thermal treatment or by the use-of specific catalysts. Thes'e specific catalysts consist in eneral of alumina or other inert siliceous or refractory materials composited with the compounds and preferably theoxides of elements selected from those in the left-hand columns of groups IV, V and VI of the periodic table. The temperature used in suchcatalytic dehydrogenations will ordinarily range from 900 to 1200" F., while employing a pressure range from sub- ApplicatiodNovember 16, 1942, Serial No. 465,698

stantially atmospheric to 100 pounds or more per square inch super-atmospheric.

Butanediols may be readily prepared-by treatment of butene-l. or butene-2 with hypochlorous acid to secure the corresponding chlorohydrin, subjecting this to the action of potassium hydroxide to obtain the alkene oxide and hydrating the latter with a d lute solution of. a strong acid such as sulfuric or perchloric acid. Butanediols are readily converted to diacetates by reaction with acetic anhydride. This reaction takes place quite readily even in theabsence of a catalyst.

In accordance with the present invention butanediol diacetates are decomposed to form butadiene and acetic acid by subjecting their vapors.

at temperatures within the range of from. about 400 to about 600 C. to contact with catalysts comprising oxides of the elements in the lefthand column of group IV'o f the periodic table including titanium, zirconium, cerium, hafnium,

and. thorium. Under these conditions and the catalytic influence of the oxides, the diacetates decompose to form butadiene and acetic acid according to the following equation: oooon. x

04H; om. zcmooon Butanedioldlacetate Butadiene Acetic acid It is obvious from the above typical equation that the formation of acetic acid in the reaction requires the abstraction of hydrogen from the butene group so that in efiect the reaction is one of dehydrogenation of the butane radical catalyzed by the oxide. In this reaction there is no formation of metal acetates nor' of. any substantial amount of acetic anhydride, although minor quantities of carbon dioxide and acetone may be formed. The preceding general description of the process and the reactions involved therein has been iven in connection with the diacetates formed by interacting butanediols with acetic anhydride. However, in place of acetic anhydride, corresponding anhydrides of other monobasic aliphatic carboxylic acids can be used alternatively. The conditions employed in connection with these other fatty acids both in the manufacture of the butanediol acid addition products and in the decomposition of these products in contact with the preferred catalysts will vary with each acid used. The'use of acetic anhydride is generally preferable on account of its greater availability and lower cost.

-Of the oxides of titanium, zirconium, hafnium, and'thorium which are alternatively utilizable with varying degrees of eiiectiveness in the step of decomposing-the butanediol acetates, the oxides of zirconium and thorium have been found to have the highest catalytic activity under a given set of operating conditions, and 'owing'to the relative cheapness and ease of preparationv of these oxides, their use is usually preferred over those of the other members of the group. The oxides of the group IV elements specified may be used singly or in various admixtures and, if desired, on relatively inert supporting materials. The various oxideswhich may be used to catalyze the diacetate decompositions may be same catalyst with varying obtained from naturally occurring sources or may be produced by precipitating the hydrated oxides by the addition of basic precipitants to solutions of salts of the elements followed by washing to remove adsorbed and occluded impurities, heating to remove water, and forming in some manner granules which can be utilized in the so-called stationary bed operations. The prepared oxides may, ii desired, be powdered and then pelleted or extruded by types of operations well-known.

of the preferred catalyst, compounds of butanediol with other mono-carboxylic aliphatic cids may also be decomposed in the presence of the degrees of effectiveness to produce butadiene. Thus butanediol dipropionates and butanediol dibutyrates may be employed as well as similar compounds of higher molecular weight acids of this series.

The following example will illustrate the operation of the process and the results obtainable,

although it is not intended to limit the scope of the method in exact correspondence with the data set forth.

One part by weight of 2,3-butanediol was treated with 2 parts by weight of acetic anhydride at approximately 50 C., for a period of two hours. The greater portion of acetic acid formed in this reaction was then removed by the acid and combined with the bined butadiene amounted to 75% distillation. The butanediol diacetate, which per volume of catalyst space.

C. and it contained some diswas not further purified, was decomposed by passing it in thevaporous state over granular zirconium oxide heated to a temperature of 485 C., using substantially atmospheric pressure and a liquid space velocity of two volumes per hour The acetic acid was recovered at 0 solved butadiene which was separated by heating C. The comof the theoretical yield and was over 1,3-butadiene as shown by absorption in molten maleic anhydride.

I claim as rnyinvention:

1. A process for producing butadiene which comprises subjecting a butanediol dialkanoate to contact with zirconium oxide at a temperature suflicient to convert it into butadiene and an alkanoic acid.

2. A process for producing butadiene which comprises subjecting a butanediol di-alkanoate at a temperature of from about 400 to about 600? C. to contact with zirconium oxide.

3. A process for producing butadiene which comprises subjecting a. butanediol di-alkanoate at a temperature of fromabout 400 to about of butadiene condensed at '78 600 C. and substantially atmospheric pressure to contact with zirconium oxide.

4. A process for producing butadiene which comprises subjecting a butanediol diacetate to contact with zirconium oxide at a temperature sufficient to convert it into butadiene and acetic acid.

5. A process forproducing butadiene which comprises subjecting a butanediol diacetate to contact at a temperature'of from about 400 to about 600 C. and substantially atmospheric pressure with zirconium oxide.

6. A process for producing butadiene which comprises contacting a butanediol di-acetate -with zirconium oxide at a temperature of from about 400 to about 600 C.

wnmAM J.. MA'I'IOX.

main portion 

